[Radiance-general] Radiance, objline, objpict etc..

[Jack de Valpine]

Hi,

I wanted to add a few comments on this.

The "-i <radius>" option to ies2rad creates a sphere of radius specified 
by -i. This sphere has a an illum type applied to it to produce light. 
The illum is modified by a brightfunc specifying the output distribution 
based on the converted photometry data. However there are a few things 
to note:

   1. an illum is invisible - however it gives off light, if you are
      having problems a good first test is to convert your ies data
      without the -i option so you will get a "light" material defined
      rather than an "illum" material
   2. ies2rad -i creates a sphere, you need to understand where the
      sphere is relative to other surface geometry such as a ceiling,
      you may have problems if your sphere cuts through other geometry
   3. an illum can specifiy an alternate material to show up in its
      place (however if you have a sphere defined via ies2rad where in
      fact there should be a ring then this will not look right):

        void glow my.glowing.source
        0
        0
        4 1 1 1 0

        void brightfunc my.illum.distribution
        <.....>
        0
        1 1

        my.illum.distribution illum my.illum.source
        1 my.glowing.source
        0
        3 1 1 1

I have always advocated that whenever anyone is using ies photometric 
data, one should create a simple test box to place the output of ies2rad 
into in order to quickly view what is going on. This way you can see if 
the things are behaving the way they need and/or if they need additional 
transforms to get things in the correct location/orientation.

In the case where you want to create more detailed geometry representing 
the fixture and perhaps a glowing source, then the thing to do is to 
create this geometry and use a glow for the source surface and then 
either enclose this in an illum sphere or other enclosing geometry or 
float a quad or ring in front of the glow (assuming relatively 
directional output) and again apply the illum distribution. However be 
aware of what Rob G. has pointed out that there will be some 
distributions that will "cut off" dependent on view angle.

To deploy multiple instances of a light into a scene you can use xform 
as I think Thomas has outlined. This will work when thing are generally 
evenly spaced. If you have a more irregular deployment then you need to 
take a look at "replmarks" (man replmarks), which will replace a 
triangular marker with whatever you want (light or other kind of 
instanced geometry).

I hope this helps.

Regards,

-Jack de Valpine

steve michel wrote:
> Hi Thomas,
>
> MARK THIS SOLVED
>
>
> I had created a 'glow' material and applying it to the same polygon in my ies.rad file. SO I got a render with my fixtures showing but still no illumination! I was trying to overlap or layer a glow material on a distribution's polygon. So you are right that the two might interfere. (But I can see where that might be useful to avoid  the extra step of two distinct polygon geometry for the same thing (which I have done before with erco fixtures 3d geometry)) 
>
>
>
> BUT The simpler method of deleting the -i option in ies2rad worked...I see the fixture and the light distribution...
>
> The next challenge is to use a single light distribution material and apply to multiple similar geometry in the scene... To isolate the problem, I've been hand editing each fixture geometry and duplicating the same ies.rad parameters to each...
>
>
> thanks to all
> Steve
>
>
>
> ----------------------------------------
>   
>> From: tbleicher at arcor.de
>> Subject: Re: [Radiance-general] Radiance, objline, objpict  etc..
>> Date: Sun, 27 Jan 2008 11:31:48 +0000
>> To: radiance-general at radiance-online.org
>>
>>
>> On 26 Jan 2008, at 18:50, steve michel wrote:
>>
>>     
>>> Rob,
>>>
>>> The fixture is a recessed fluorescent with a flat translucent lens;
>>>       
>> Being recessed the fixture will have no uplight component. Did you
>> check the orientation the IES file will have in the scene? Typically
>> major output direction will point downwards (-z). For a downlight you
>> should not need any rotation, just lift (xform -t) the *.rad file to
>> the right height and place in your scene.
>>
>>     
>>> therefore my needs are simply to show a glow for the lens on the same
>>> plane as the ceiling. I applied the ies distribution to a simple  
>>> polygon.
>>>       
>> Did you create the polygon yourself? Ies2rad (without -i option!) will
>> do that and you don't need any further polygons. They will only  
>> interfere
>> with you're distribution. The only problem is that the polygon will have
>> the size of the luminous area not the of the actual fitting.
>>
>>
>> Regards,
>> Thomas
>>
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>>     
>
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-- 
# Jack de Valpine
# president
#
# visarc incorporated
# http://www.visarc.com
#
# channeling technology for superior design and construction

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